Development of skeletal microarchitecture and biomechanics over 2 years following 6 month intragastric balloon insertion in obese adolescents

Abstract

Background: A reduction in bone mass in adults and adolescents has been observed following Roux-en-Y bypass surgery with an increase in fracture risk reported in adults. However, the intragastric balloon (IGB) is a less invasive bariatric procedure. Objective and hypotheses: Given obese adolescents are at greater risk of fracture we studied the impact of a 6 month IGB insertion on skeletal mass, geometry and strength over 2 years. Method: We recruited 12 adolescents aged 13.8 to 16.8 years, BMI > 3.5 SD, Tanner stage 4/5 to undergo IGB placement. Subtotal body and lumbar spine (LS:L1-L4) were measured by DXA and radial/tibial cortical and trabecular bone parameters were evaluated by high resolution pQCT imaging at 0, 6 and 24 months. Skeletal biomechanical parameters were defined by miocrofinite element analysis. Results are expressed as (mean difference (95%CI), significance(p)). Results: At 6 months BMI SDS fell by -0.27 SD (-0.43, -0.10), p = 0.005, due to a reduction in perecntage fat mass of - 2.0 (-3.9, - 0.03), p = 0.05. Weight loss was not sustained at 2 years. At 6 months subtotal body BMC (g) (60.7(5.5,115.9), p = 0.03),LSBMC (g) (2.5(1.4,3.6), p = 0.001) and LS BA (cm2) (0.8(0.4,1.2), p = 0.002) all demonstrated expected age appropriate increases. Over 2 years there were overall increases in total body BMD (g/cm2) (0.04(0.01, 0.06), p = 0.01), LS BMC (g) (5.3(1.0,9.5), p = 0.02) and LS BA (cm2) (2.0(0.9,3.0), p = 0.003). At the tibia, consistent gains were seen from baseline to 2 years in cortical area (mm2) (10.1(1.7,18.5), p = 0.02) and cortical thickness (mm) (0.09(0.002,0.173), p = 0.04). Gains were only seen in cortical (14.0(8.3,19.6), p< 0.001) and trabecular (4.1(0.5,7.6), p = 0.03) BMD (g/cm3) BMD at the radius at 6 months. Over 2 years bone stiffness (S, kN/mm) and ultimate failure load (F.Ult, kN) at the radius (S = 4.1(1.3,6.9), p = 0.01), (F.Ult = 0.2 (0.1,0.3), p = 0.004) and tibia (S = 7.5 (0.6,14.5), p = 0.04), (F.Ult = 0.5(0.1, 0.9), p = 0.02) increased. Conclusion: In the short term, an IGB placement offers significant reduction in BMI SDS. Unlike other bariatric procedures, bone accrual during adolescence continued at a time when bone mass accrual is critical.L6159158572017-05-09 <br />